Directional Random Lasing in Liquid Crystal Infiltrated Metasurfaces

Abstract: Random lasers (RL) emit light through multiple scattering in disordered gain media, typically resulting in isotropic emission with limited directionality control. Controlling RL emission direction in compact systems remains a challenge. Here we report directional random lasing achieved by infiltrating dye-doped nematic liquid crystals into a nanostructured silica metasurface. By adjusting pump energy, we induce a transition from uniform angular photoluminescence to a strongly directional emission peak at large angles in the amplified spontaneous emission and RL regimes. This directionality arises from enhanced spatial coherence in the strong scattering regime, enabling coupling of guided random-laser modes to high-angle diffraction through the metasurface grating. Our system demonstrates wide-angle RL beam steering at submicron scale without complex external components. These results provide a straightforward method to control RL emission directionality, advancing tunable coherent light sources and metasurface-based photonic applications.